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PubMedDate not supplied

Comparisons of cardiac output in supine and lateral positions.

Cardiac output was measured by thermodilution in 51 adult postcardiac surgical patients using three positions, supine, right lateral, and left lateral, each with 20 degrees backrest elevation. Measurements were taken 4 to 24 hours (M = 10.58) after surgery. Mean cardiac output was significantly different in the three positions, p = .03. This difference resulted from changes in stroke volume, p = .004, rather than changes in heart rate, p = .12. The largest variation occurred between cardiac outputs measured in the supine position and those measured in the left lateral position. Patients at greatest risk for variations in cardiac output with lateral postural change were those with a cardiac index less than 2.3 L/min/m2, those in whom the time elapsed since surgery was less than 12 hours, and those receiving either vasoactive drugs or mechanical ventilation. These results suggest that nurses need to measure cardiac output using a supine position to control for physiological changes that may occur with lateral postural change.

Adult↗
PubMed1995

Comparison of continuous with intermittent bolus thermodilution cardiac output measurements.

BACKGROUND: Few complete studies have been published to validate the agreement between continuous cardiac output and intermittent thermodilution cardiac output. OBJECTIVE: To analyze the agreement between cardiac output measurements by the continuous thermodilution method and the intermittent bolus thermodilution method, using a continuous cardiac output catheter in postoperative cardiothoracic surgery patients. METHODS: A convenience sample of 14 adult cardiothoracic surgical patients with thermodilution pulmonary artery catheters placed preoperatively was used. A total of 214 comparison measurements of cardiac output by both the continuous and intermittent thermodilution methods were taken on patient admission to the critical care unit, every 4 hours, and with any change greater than 10% from baseline readings. RESULTS: The intraclass correlation between continuous cardiac output and intermittent cardiac output was .89. The limits of agreement were -1.34 to 1.18 L/min, indicating that in 95% of readings the difference between continuous cardiac output and intermittent cardiac output were within this range. CONCLUSIONS: The continuous cardiac output monitoring method shows clinically acceptable agreement with the intermittent cardiac output method.

Adult↗
PubMed1994

Factors associated with the development of persistently depressed cardiac output during the first year after cardiac transplantation.

The purpose of this study was to determine factors associated with the development of a persistently depressed cardiac output during the first year after cardiac transplantation. With this aim in mind, the records of 133 consecutive patients undergoing orthotopic cardiac transplantation and surviving for > or = 1 year after transplantation were reviewed. For each patient, the mean cardiac index for each of the 3-month periods, 0-3, 4-6, 7-9, and 10-12 months after transplantation was calculated. Of the 133 patients, 19 (14%) had a mean cardiac index < 2.4 l/min/m2 during > or = 3 of these 3-month periods. The pre- and post-transplantation clinical, immunologic, and hemodynamic data of these 19 patients (study group) were compared with the remaining 114 patients (control group). Compared with the control group, the patients in the study group were older (56 +/- 5 vs. 46 +/- 15 years; p = 0.0001), more frequently had ischemic heart disease as the original diagnosis (58 vs. 37%; p < 0.05), had a lower preoperative cardiac index (1.91 +/- 0.53 vs. 2.71 +/- 1.0 l/min/m2; p = 0.0001), more frequently did not receive perioperative anti-T cell therapy (47 vs. 25%; p = 0.046), and had a greater median number of infections during the first year after transplantation (5 vs. 3; p = 0.027). However, only one factor--a low preoperative cardiac index--emerged as an independent predictor of the development of a persistently depressed cardiac index during the first year after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1989

Evaluation of heavy water for indicator dilution cardiac output measurement.

We evaluated deuterium oxide (D2O) as a tracer for cardiac output measurements. Cardiac output measurements made by thermodilution were compared with those made by indicator dilution with D2O and indocyanine green as tracers. Five triplicate measurements for each method were made at intervals of 30 minutes in each of 9 anesthetized, mechanically ventilated goats. Cardiac output ranged between 0.68 and 3.79 L/min. The 45 data points yielded a correlation coefficient of 0.948 for the comparison of D2O indicator dilution cardiac output measurements with thermodilution measurements and a linear regression slope of 1.046. D2O indicator dilution measurements were biased by -0.11 +/- 0.22 L/min compared with thermodilution measurements and had a standard deviation of +/- 0.12 L/min for triplicate measurements. Hematocrits ranging between 20 and 50 vol% had no effect on optical density for D2O. D2O is more stable than indocyanine green and approximately one-tenth the price (40 cents per injection compared with $4). The basic instrumentation cost of approximately $9,000 is an additional initial expense, but provides the ability to perform pulmonary extravascular water measurements with a double-indicator dilution technique. D2O has potential as a tracer for the clinical determination of indicator dilution cardiac output measurements and pulmonary extravascular water measurements.

Animals↗
PubMed1976

Direct Fick application for measurement of cardiac output in rat.

The direct Fick procedure for cardiac output determination in rat was validated by simultaneous comparison with electromagnetic flowmeter techniques. Significant coefficients of correlation were obtained between absolute cardiac output values (r = 0.789, P less than 0.001), increases (r = 0.768, P less than 0.001) and decreases (r = 0.672, P less than 0.01) in cardiac output detected by the two methods. As demonstrated in other species, cardiac output values of the Fick procedure in the rat were between 40 and 58% greater than respective electromagnetic flow probe values; however, percent changes in cardiac output obtained by the two methods were similar. The larger values of cardiac output obtained by the direct Fick method may be related, to a great extent, to the distribution of blood flow to the coronary and bronchial circulations. Fick cardiac output measurements were reproducible within rats, and the degree of variation in values among rats was similar to that obtained with the flowmeter procedure. The result indicate that the Fick meth od provides a valid estimation of cardiac output in the rat, with the ability to detect moderate changes (22-36%) in cardiac output.

Animals↗
PubMed2002

Lack of agreement between thermodilution and fick cardiac output in critically ill patients.

STUDY OBJECTIVE: s: Individual comparison of cardiac output via intermittent thermodilution and Fick technique over a wide range of cardiac outputs. DESIGN: Prospective clinical investigation. SETTING: Multidisciplinary ICUs of two teaching hospitals in Vancouver, British Columbia. PARTICIPANTS: Eighteen critically ill patients who had pulmonary and systemic arterial catheters and in whom active support was being withdrawn. INTERVENTIONS: Measurement of thermodilution cardiac output and calculation of Fick cardiac output while support was withdrawn. Active support was withdrawn in a three-step process: removal of vasopressors followed by decrease in fraction of inspired oxygen to 0.21, and finally removal of mechanical ventilation. MEASUREMENTS AND RESULTS: Simultaneous Fick and thermodilution cardiac outputs were obtained over a wide range. Fick calculated cardiac outputs were obtained using the Fick equation with oxygen uptake (O(2)) being measured with indirect calorimetry. O(2) determinations were made using five measurements over 5 min, with the mean being used for subsequent analysis. Thermodilution cardiac outputs were determined by the mean of five measurements, with the first being discarded. Coefficient of variation was calculated for the O(2) and thermodilution cardiac outputs. One hundred thirty-six simultaneous cardiac outputs were obtained in 18 patients with a mean APACHE (acute physiology and chronic health evaluation) II score of 25.5. The range of cardiac outputs was 1.39 to 16.95 L/min. Linear regression analysis found a good correlation of the data sets, with an R of 0.85. Bias and precision calculations found a bias of - 0.17 L/min with the upper and lower limits of agreement being 2.96 L/min and - 3.30 L/min, respectively. In patients with high cardiac outputs (> 7 L/min), the bias was - 1.90 with the limits of agreement being 1.87 L/min and - 5.67 L/min. The coefficient of variation for O(2) was 4.6% and for thermodilution cardiac output was 7.75%. CONCLUSIONS: There was good consistency of each of the measurements with a low coefficient of variation. The bias for the whole group was small, but the limits of agreement extended into a clinically relevant area, resulting in a lack of agreement. In patients with high cardiac outputs, the Fick tended to consistently produce higher cardiac outputs compared to thermodilution, suggesting a systematic error.

Adult↗
PubMed2006

[Circulation monitoring of critically ill patients with the Pulse Contour Cardiac Output system].

The Pulse Contour Cardiac Output (PiCCO) monitoring system measures cardiac output with high precision and accuracy. The system may replace the pulmonary artery catheter in most critically ill patients because the rate of serious complications may be lower. Whether the use of dynamic or static fluid monitoring by PiCCO will result in better outcomes should be assessed by studies using clinically relevant end points.

Blood Circulation↗
PubMed1996

Doppler measurement of cardiac output during cardiopulmonary resuscitation.

OBJECTIVE: To estimate the cardiac output produced by external cardiac compression during standard cardiopulmonary resuscitation performed by two groups of operators with different levels of experience and training. METHODS: Cardiac output was measured by Doppler aortovelography. All patients included in the study had necropsy examinations. Only patients without evidence of pulmonary embolism, myocardial rupture, aortic valve disease, or acute depletion of the intravascular volume were included. RESULTS: 31 patients presenting to the accident and emergency department suffering from non-traumatic cardiac arrest had cardiac output measurements made during resuscitation. Eleven patients were excluded after necropsy examination. The median cardiac index for the 20 study patients was 3.2 L min-1 m-2. The cardiac output produced by massage by less experienced personnel (median 1.2 L min-1 m-2) was significantly less than that produced by those fully trained in the technique (median 3.2 L min-1 m-2; P < 0.01 95% confidence interval -2.36 to -1.29). The amount of resuscitation related trauma was no greater than in other published series. CONCLUSIONS: Differences in cardiac output during external cardiac compression are related to experience with the technique.

Adolescent↗
PubMed1984

Cardiac output after burn injury.

Cardiac output after burn injury has been measured by the non-invasive method of impedance plethysmography. An initial study of 143 normal subjects was undertaken in order to investigate variations in cardiac output with age. Fifteen patients were monitored during resuscitation after extensive burns. Fourteen patients showed a depression of stroke volume below the lower limits of the normal range, derived from the initial study on normal people.

Adolescent↗
PubMed2002

Pulmonary artery blood temperature and the measurement of cardiac output by thermodilution.

Thermodilution cardiac output measurement assumes that the temperature within the pulmonary artery is stable during the measurement period. This may not be achieved in clinical practice because of temperature changes that are not solely produced by the thermal indicator. Such temperature changes constitute thermal noise. Thermal noise and how it may interfere with measurement is discussed with reference to both the injectate and the thermal filament methods of thermodilution cardiac output measurement.

Blood Physiological Phenomena↗
PubMed1983

The effect of cardiac denervation and beta-blockade on control of cardiac output in exercising dogs.

Normal and cardiac denervated dogs, with an electromagnetic aortic flowprobe implanted at least 14 days before the experiments, ran at different speeds on a 25% graded treadmill. The experiments were carried out before and after blockade of betareceptors in the heart by PO administration of 125 mg X kg-1 practolol per day. Changes in stroke volume, heart rate, and cardiac output were measured. After beta-adrenergic blockade, only two of the seven dogs with denervated hearts were prepared to run at a limited number of speeds. Time constants of the cardiac output changes at the onset of exercise were significantly different (P less than 0.001) for the normal (11.5 +/- 0.7 s, mean +/- SEM) and the denervated dogs (29.5 +/- 1.1 s), but in normal dogs did not change with practolol (11.8 +/- 0.8 s). The steady state relationship between cardiac output (CO) and work per unit time performed on the treadmill (P) was for normal dogs: CO = 156 + 1.55P, for normal dogs after practolol treatment: CO = 156 + 0.43P (slope significantly different, P less than 0.05), and for dogs with denervated hearts: CO = 121 + 2.06P (not significantly different from normal dogs). It was concluded that changes in the venous or arterial system alone are not sufficient to increase cardiac output appreciably during exercise. The magnitude of the cardiac output increase depends more on the presence of intact beta-receptors than on the presence of intact cardiac nerves.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Hemodynamic-induced changes in aortic valve area: implications for Doppler cardiac output determinations.

UNLABELLED: Monitoring cardiac output (CO) by transesophageal echocardiography involves measurements of ascending aortic flow and an initial measurement of aortic valve area (AVA). Hemodynamic-induced changes in AVA are a potential source of error for this simplified method. Our goal was to quantify these changes in AVA and their effects on CO calculations. In 17 anesthetized patients, a dobutamine infusion was titrated to achieve a 50% increase in ascending aortic flow velocity (V(max)). Hemodynamic and echocardiographic variables, including V(max) and planimetry of AVA, were determined at baseline and at maximal dobutamine dose. Dobutamine produced a 3.0 +/- 1.4 L/min increase in CO, a 54.5% +/- 19.6% increase in V(max), and a 50.6% +/- 34.2% increase in systolic blood pressure. AVA increased by 4.3% +/- 2.6% during dobutamine infusion (P < 0.001). The simplified CO method, which does not account for increases in AVA, produced a 0.32 +/- 0.24 L/min underestimation of CO. This investigation demonstrates hemodynamic-induced changes in AVA. The use of a single AVA measurement for all subsequent CO calculations introduces a clinically acceptable degree of error, supporting a simplified CO protocol requiring less probe manipulation and reduced procedural time. IMPLICATIONS: An intraoperative dobutamine infusion was used to increase aortic blood flow and demonstrate hemodynamic-induced changes in aortic valve area. These valve-area changes affect the accuracy of Doppler cardiac output determinations.

Adult↗
PubMed1998

[Comparison of pulse dye densitometry and thermodilution method in cardiac output measurement].

We measured cardiac outputs at forty points from five patients by pulse dye densitometry and compared these with those measured by thermodilution method. We obtained a good correlation (y = 1.090 x = . 0.030, n = 40, 5 cases) and small mean bias (0.348 +/- 0.830 l.min-1, n = 40, 5 cases) between the two methods. We suggest that this method of cardiac output measurement by pulse dye densitometry is not invasive and may be more effective than that by thermodilution method.

Cardiac Output↗
PubMed2005

Transcutaneous fluorescence dilution cardiac output and circulating blood volume during hemorrhagic hypovolemia.

BACKGROUND: Cardiac output and circulating blood volume are important parameters for assessing cardiac function in the intensive care setting and during major surgeries. The authors tested in an animal model of hemorrhagic hypovolemia the feasibility of measuring these parameters simultaneously by transcutaneous fluorescence monitoring of an intravenous bolus injection of indocyanine green. METHODS: Fluorescence dilution cardiac output was measured in seven anesthetized rabbits and compared to thermodilution cardiac output. The optical probe used to excite the indocyanine green fluorescence was in contact with the skin above the ear artery. Local heating enhanced blood perfusion of the measurement site. Cardiac output was measured during baseline conditions, during hemorrhagic hypovolemia, and after partial restoration of the blood volume with reinfused blood. Estimates of the circulating blood volume were simultaneously obtained from the analysis of the fluorescence dilution traces. RESULTS: Cardiac output measured by fluorescence dilution (thermodilution) averaged 455 +/- 16 (450 +/- 13) ml/min in baseline conditions and 323 +/- 15 (330 +/- 13) ml/min during hypovolemia. Fluorescence dilution cardiac output was linearly related to thermodilution cardiac output (slope = 1.13 +/- 0.05, ordinate = -50 +/- 19 ml/min, R = 0.92). Interanimal differences explained most of the variance between cardiac output estimates obtained with the two techniques. Circulating blood volume decreased from 204 +/- 5 ml in baseline conditions to 174 +/- 8 ml after bleeding and reflected blood volume changes in this acute bleeding-reinfusion model. CONCLUSIONS: The study extends the applicability of the fluorescence dilution technique for cardiac output measurement to hypovolemic conditions and demonstrates its ability to produce accurate estimates of the circulating blood volume in experimental animals.

Algorithms↗
PubMed1995

Determination of cardiac output by echocardiography.

To determine cardiac output using a non-invasive manner, we examined correlations between cardiac output values determined by ten different kinds of echocardiography and those determined by the thermodilution method. With respect to the M-mode method, one of the rotary ellipsoid approximation methods using a short axial section at the papillary muscular level, namely the GIBSON method, showed the highest correlation with the thermodilution method (r = 0.84; p < 0.01). Among the Doppler mode method, the highest correlation (r = 0.93; p < 0.01) was exhibited by the method in which the area of the luminal section of the outflow tract was accurately measured using a trace method on a short axial cross section of the tract flowing out of the left ventricle. These findings suggest that it is possible to determine cardiac output by echocardiography in the same was as with the thermodilution method. Moreover, non-invasive determination methods using echocardiography have been confirmed to be highly beneficial in clinical settings.

Animals↗
PubMed2005

The 2-bodied continuous cardiac output catheter.

Continuous cardiac output (CCO) pulmonary artery catheters (PACs) are used in cardiac surgical patients for hemodynamic monitoring. This is an invasive technique; therefore, it has well-known mechanical and infectious complications related to its use. Associated problems, more commonly noticed, are catheter malfunctions and malpositions. We present a case in which a CCO catheter appeared to have a double body on radiologic diagnosis. This resulted in extra radiography for rechecking and careful clinical reevaluation of the monitored data.

Adult↗
PubMed2001

Lack of association between carotid artery volume blood flow and cardiac output.

OBJECTIVE: The correlation of cardiac output and cerebral perfusion is unclear. We tested this potential association by correlating cardiac output data obtained by echocardiography and cerebral blood flow data as determined by color M-mode measurements of carotid artery blood flow. METHODS: We studied 43 patients with a broad spectrum of cardiac performance by means of transthoracic echocardiography. In these patients, different cardiac indices such as stroke volume, ejection fraction, and heart minute volume were determined. The data were correlated with volumetric flow measurements (color M-mode duplex system) of the common carotid arteries bilaterally. RESULTS: Heart minute volume ranged from 1.632 to 9.836 mL/min (mean +/- SD, 4.652 +/- 1.621 mL/min); ejection fraction ranged from 18% to 76% (mean, 48% +/- 16%). The relative fraction of carotid volume flow compared with heart minute volume was 15% +/- 6%. There was no correlation between ejection fraction, stroke volume, or heart minute volume and absolute volume flow in the carotid arteries when being adjusted for age. There was a highly significant inverse correlation (r = -0.8; P < .0001) of the relative fraction of the carotid volume flow (carotid volume flow/heart minute volume [percent]) and the heart minute volume. CONCLUSION: Our data support the concept that cerebral blood flow is independent of cardiac output.

Cardiac Output↗
PubMed1986

Validation and application of single breath cardiac output determinations in man.

Cardiac outputs by single breath (Qsb) and Fick (Qf) procedures were compared in five healthy males during supine rest and exercise with Qf ranging from 6-19 L X min-1. The prolonged exhalation (SB) was not controlled. The Qsb calculations incorporated an equation of the CO2 dissociation curve and a "moving spline" sequential curve-fitting technique to calculate the instantaneous R from points on the original expirogram. The resulting linear regression equation for all 38 comparisons obtained (r = +0.76, p less than 0.001, mean difference +/- S.D. = 2.93 +/- 2.72 L X min-1) indicated a 24% underestimation of Qf. A substantial portion of the variability during exercise (n = 28) was due to a difference in alveolar ventilation between the time of the mixed expired (E) gas collection and the SB maneuver. When Qsb was corrected (Qsb) by a linear regression based on the difference between Re and Rsb during exercise and by adding 2.44 L X min-1 at rest (the mean difference), the relationship was greatly improved (Qsb = 0.14 + 0.99 Qf, r = +0.93, mean difference +/- S.D. = 0 +/- 1.47 L X min-1). A subsequent study during upright rest and exercise to 80% of VO2max in 6 subjects indicated a close linear relationship between Q'sb and VO2 for all 95 values obtained (r = +0.94), with slope and intercept close to published studies utilizing invasive cardiac output measurements. Considerations of measured blood gases in relation to estimated values suggested that underestimates of Qf arose, at least in part, from arterial desaturation during the SB maneuver. Detailed computational procedures are provided for implementing this improved Qsb procedure.

Adult↗